Build steps


This page details the purpose of each step in the project build process. Running steps manually is generally not needed for development as you may use directly the instructions from the Building page.

Building the documentation

The project documentation is built with Sphinx. The documentation sources are available in the docs-src directory.

To build the documentation and to open it in your browser, run:

$ cosmk doc --build
$ cosmk doc --open


To build the software components of CLIP OS, we use a SDK based on Gentoo Hardened. The SDK container is created by importing the upstream stage 3 root filesystem and updating it with a current copy of the upstream Gentoo Portage tree to include various utilities. If unavailable, the SDK is automatically imported from the configured CI or build locally, and may be manually rebuild from scratch using:

# Remove the current SDK container images
$ podman rmi <registry>/clipos/sdk:<version>       # podman
$ sudo docker rmi <registry>/clipos/sdk:<version>  # Docker

# Set empty URLs for the 'registry' in the 'ci' section of the 'config.toml'
$ $EDITOR config.toml

# Bootstrap the SDK
$ cosmk bootstrap sdk


The main rootfs in CLIP OS is called Core, and can be built using:

$ cosmk build core
$ cosmk image core
$ cosmk configure core
$ cosmk bundle core

EFI boot partition

EFI boot is the only supported boot method. The content of the EFI boot partition (bootloader, kernel image, etc.) is built using:

$ cosmk build efiboot
$ cosmk image efiboot
$ cosmk configure efiboot
$ cosmk bundle efiboot

Initial state for QEMU test image

To test the resulting OS in a QEMU virtual machine, we generate a tarball with the configuration to be installed in the system state partition:

$ cosmk bundle qemu

QEMU image

In order to test the resulting OS, we use libguestfs tools to assemble a QEMU qcow2 disk image to boot inside a EFI enabled virtual machine using libvirt. The qcow2 QEMU image may be assembled using:

$ cosmk test --qemu

Testbed environment setup

To setup the virtual testbed environment with Vagrant and libvirt, use:

$ cosmk test --setup

Testing the QEMU image

To setup a EFI & QEMU/KVM enabled virtual machine with libvirt, use:

$ cosmk test --start

Caching and binary packages

To speed up the build process during development, we keep the output of each build action in the cache and out folders. The cache directory keeps binary packages and logs. The out directory keeps the intermediate rootfs and temporary files that are safe to remove before a rebuild.

By default, the cosmk tool will clear the out folder and reuse cached output (mainly packages) to speedup iterative development builds. To restart everything from scratch:

$ rm -rf out cache
# If using Docker or rootfull podman
$ sudo rm -rf out cache

Pre-built binary packages by a continuous integration infrastructure (GitLab CI)

We use GitLab CI to automatically build CLIP OS. The GitLab CI configuration and build scripts are tracked in the clipos/ci repository and the resulting artifacts are made available at

To download CI-built binary packages from the last successful CI job, use:

$ cosmk cache

SDKs are automatically downloaded from the CI if configured in config.toml.